package com.kmip.server.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value; // Example import
// import org.springframework.beans.factory.annotation.Autowired;
// import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Primary;
import org.springframework.stereotype.Service;
// import org.springframework.web.client.RestTemplate; // Removed: Add dependency if needed later

import javax.crypto.SecretKey;
import javax.crypto.KeyGenerator; // Changed package from java.security
import java.security.SecureRandom;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
import java.util.UUID;

@Service("externalKms")
@Primary
public class ExternalKeyManagementService implements KeyManagementService {

    private static final Logger log = LoggerFactory.getLogger(ExternalKeyManagementService.class);
    
    // @Autowired
    // private RestTemplate restTemplate;
    
    // @Value("${kms.endpoint.url}")
    // private String kmsEndpointUrl;

    @Override
    public String createSymmetricKey(String algorithm, int keyLength, Map<String, Object> attributes) throws KmipException {
        log.info("Using ExternalKMS to create Symmetric Key - Algorithm: {}, Length: {}", algorithm, keyLength);

        // --- Commented out REST API Call Example ---
        /* 
        String createKeyUrl = kmsEndpointUrl + "/keys";
        Map<String, Object> requestBody = new HashMap<>();
        requestBody.put("algorithm", algorithm);
        requestBody.put("keyLength", keyLength);
        requestBody.put("attributes", attributes); // Pass relevant attributes
        
        try {
            // ResponseEntity<Map> response = restTemplate.postForEntity(createKeyUrl, requestBody, Map.class);
            // if (response.getStatusCode().is2xxSuccessful() && response.getBody() != null) {
            //     String keyId = (String) response.getBody().get("keyId");
            //     log.info("Successfully created key via external KMS. Key ID: {}", keyId);
            //     return keyId;
            // } else {
            //     log.error("Failed to create key via external KMS. Status: {}, Body: {}", response.getStatusCode(), response.getBody());
            //     throw new KmipException("External KMS key creation failed with status: " + response.getStatusCode());
            // }
            log.warn("External KMS REST call is commented out.");
            throw new KmipException("External KMS call not implemented."); // Throw exception as it's commented out
        } catch (Exception e) {
            log.error("Error calling external KMS for key creation: {}", e.getMessage(), e);
            throw new KmipException("Failed to communicate with external KMS", e);
        }
        */
        // --- End Commented Out Example ---
        
         // --- Temporary Fallback/Placeholder --- 
         log.warn("External KMS REST call is commented out. Falling back to local generation (REMOVE THIS LATER).");
         try {
             return generateLocallyForFallback(algorithm, keyLength);
         } catch (Exception e) {
             throw new KmipException("Fallback local key generation failed", e);
         }
         // --- End Temporary Fallback --- 
    }

    private String generateLocallyForFallback(String algorithm, int keyLength) throws Exception {
        KeyGenerator keyGen = KeyGenerator.getInstance(algorithm);
        keyGen.init(keyLength, new SecureRandom());
        SecretKey secretKey = keyGen.generateKey();
        String uniqueID = UUID.randomUUID().toString();
        log.info("(Fallback) Generated local key with ID: {}", uniqueID);
        // NOTE: This key is NOT stored anywhere in this fallback!
        return uniqueID;
    }

    @Override
    public Optional<SecretKey> getSymmetricKey(String uniqueID) {
        log.info("Attempting to retrieve key ID {} from External KMS", uniqueID);
        // TODO: Implement REST call to external KMS to get key material by ID
        log.warn("External KMS getSymmetricKey not implemented.");
        return Optional.empty(); // Return empty for now
    }
} 